Quality Change in Plug Seedlings of Three Indigenous Medicinal Plants after Short-term Cold Storage

To test the quality change of seedlings of three domestic medicinal plants raised in plug trays, a short term storage experiment was conducted. Seedlings were kept in growth chambers for two weeks at 4 or $8^{\circ}C$ temperature combined with 0 or $5{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD. Quality of glasshouse-raised seedlings was assessed after two weeks of cold storage in the growth chamber and one week of acclimation in the greenhouse. After two weeks of storage in the growth chamber of Perilla frutescens var. acuta Kudo, plant height was the greatest in the treatment $8^{\circ}C$ combined with $0{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD. Internode length of P. frutescens var. acuta Kudo was the greatest in the treatment of $4^{\circ}C$ combined with $0{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD. After one week of acclimatization in a glasshouse, the growth and development, such as plant height, internode length and leaf size, were greater in the $8^{\circ}C$ combined with $5{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD than in the other treatments. After two weeks of storage in the growth chamber of Sophora tonkinensis, plant height increased more in the treatment of $4^{\circ}C$ than $8^{\circ}C$. After one week of acclimatization in a glasshouse, number of leaves did not change in the treatment of $4^{\circ}C$ combined with $0{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD, but it increased in the other treatments. Leaf width increased more under the dark than light condition. Leaf length did not observably change in any treatments. After two weeks of storage in the growth chamber, plant height of Angelica gigas Nakai was the greatest in the treatment of $8^{\circ}C$. Number of leaves was the greatest in the treatment of $8^{\circ}C$. Leaf growth was greater under dark than light condition. These results suggested that optimal storage environment was $8^{\circ}C$ combined with $5{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD for P. frutescens var. acuta Kudo, and $4^{\circ}C$ combined with $0{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD for S. tonkinensis and A. gigas Nakai. Hence, proper combination of temperature and PPFD were necessary for better storage, and acclimatization and growth, thereafter, of the plug seedlings of theses plant species.